Process of treating refractory ores.



. be as nearly as possible the theoretical amount in some cases less or more.

aflinities,as chlorids and oxychlorids, by vola- UNITED STATES Patented October 20, 1903;

PATENT ()FFICE.

EDWIN O. POHLE AND STUART CROASDALE, OF DENVER, COLORADO,

ASSIGNORS TO METAL VOLATILIZATION COMPANY, OF PHILADEL- PHIA, PENNSYLVANIA, A CORPORATION OF NEW JERSEY.

PROCESS OF TREATING REFRACTORY ORES.

SPECIFICATION forming part of Letters Patent No. 741,712, dated October 20, 1903. Application filed January 23, 1900. Renewed December 3, 1900. Serial No. 38,660. (No s ecimens.)

To all whom it may concern.-

Be it known that we, EDWIN O. POHLE and STUART CROASDALE, citizens of the United States, residing at Denver, in the county of Arapahoe and State of Colorado, have jointly invented certain new and useful Improvements in Processes of the Reduction of Refractory Ores, of which the following is a specification.

. Our invention, statedin general terms, consists of a method of treating refractory ores byoxidizing, roasting the ores together with definite percentages of a chlorid of an alkaline or alkaline-earth metal and sulfur while stirring or rabbling to effect'a complete removal of the gold, silver, lead, copper, antimony, bismuth, and other metals of similar chemical tilization in the forms of fume mixed with the products of combustion of the roasting process and by subsequently collecting such volatilized values of metallic chlorids and oxychlorids in suitable condensing-chambers.

We use the word completely in a commercial sense, and mean thereby ninety per cent. or more of the metals contained in the ores. We thereby condense the valuable material into small bulk for shipment to smelters or refiners or for subsequent treatment on the ground and leave the gangue or worthless matter, containing a stable alkaline sulfate, to be disposed of without further handling and expensive treatment. This removal of the metallic values from the ores is accomplished in one operation under the following conditions: The percentage of sulfur should required to form the sulfid of the base metals (as distinguished from gold and silver) to be volatilized, and more will occasion needless waste, although such actual combination as sultid is unnecessary, and the sulfur may therefore be either free, combined as sulfid, or exist as a sulfate that is decomposed by heat in the presence of a chlorid of an alkaline or an alkaline-earth metal, and such percentage of sulfur should be preferably from two to five per cent. when none of the base metals are present, although it may be In regard to pre cious-metal ores the excess of both salt and sulfur is required because of the relatively small amount of the metals in proportionto' the gangue, and without using such excess no substantial mixture could be obtained. If the ore contains the requisite amount of sulfur, it is used in its natural condition. If it does not, or if it contains too much, sulfuris either added or is partially removed by preliminary roasting. The percentage of alkaline haloid present is,because of its partial volatilization as such, one and one-fourth to one and one-half times the theoretical amount required to form, on one hand, the normalhaloids of the base metals that are to be volatilized, and, on the other hand, the sulfate of the alkaline or alkaline-earth metals, according to the satisfac-.

tion of chemical affinities and the accomplishmeut of double decomposition, and should be ten per cent, more or less, when none of the base metals mentioned are present, or, in other words, the percentage of alkaline or alkalineearth haloid should also be from one and one-fourth to one and one-half times the theoretical amount required'to form the normal sulfate of the alkaline or alkaline-earth metal or base with the sulfurin the ores added thereto. These n1aterials-namely, the alkaline or alkaline-earth haloid, sulfur, and the metal value to be recovered-must be present in the proper certain definite quantitative relation to each' other for satisfying chemical affiuities in order to practice our process for 'the treatment of ores in the most advantageous manner-an excess beyond such as might be required, for example, of salt to compensate for volatilization thereof would result in waste-and this is well explained by the following reaction:

in which X represents the alkaline-metal base; R, the diad metal to be volatilized and removed from the ore; S, the sulfur; Cl, the chlorin, and O the oxygen. This equation for metals of other valances may be suitably changed and accurately written.

Our process is especially adapted to lowgrade silicious or dry or, in otherwords, refractory gold, silver, lead, andcopper ores,

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whether these metals occur singly or all together in one ore, provided none of them ocour in a metallic state, except that such metallic particles are in a fine state of division. It is equally applicable to ores of any metal when the chlorid or oxychlorid of that metal may be volatilized.

The mode of practicing our invention is as follows: The ore, salt, and sulfur or sulfid, in case sufficient sulfur is not present in the ore, should be pulverized, so as to pass through a screen having eighteen or more meshes to the linear inch, although we do not confine ourselves to this degree of fineness for all ores. The crushed material is thoroughly mixed and is constantly stirred, rabbled, or agitated while being subjected to an oxidizing roast in any suitable type of roasting-furnace at a bright cherry-red heat to a bright yellow heat or a temperature of 900 to 1,200 centigrade until 'all fumes cease to come off. The ore mixture should be charged at once into the lower temperature specified and heated gradually, as is ordinarily done in roasting or desulfurizing. As just stated, during the process of roasting and volatilization the ore mixture should be stirred or rabbled constantly, and in no case should it be allowed to fuse or cinter, since such fusion or cintering prevents complete volatilization. No artificial blast is required, save the necessary suction or exhaust to withdraw the fumes from the furnace to force them through the condensing chambers. When the fumes cease to be given off from the ore in the furnace, the roasted material in the furnace is withdrawn and discarded, having been deprived of its valuable contents. In this manner we save frequent handling of the large quantity of the worthless material and obtain the values in concentrated form, as chlorid and oxychlorid, which may be treated in any of the known methods for the separation of the different metals when obtained in that condition. In condensing these fumes they are drawn from the furnace through a cooling-chamber by a suction or exhaust of any form, during which process a portion of them deposit out of the products of combustion, and the remainder of the fumes contained therein are finally collected by filtering the furnace -gases through textile or mineral fabrics, or by passing them through towers filled with refactory or other material cooled by sprays of water, or by any suitable means of condensation and collection.

By this process we extract completely the valuable metal or metals from their ores by volatilization as chlorids and oxychlorids without fusing or cintering the ore, without the use of artificial blasts of air other than the necessary exhaust or suction to remove the fumes from the roasting-furnace,and force them through the condensing-chambers, and without subsequent lixiviation, smelting, or other metallurgical treatment of the roasted material in the furnace.

When we state that we extract completely by volatilization, we wish to be understood as speaking in commercial terms, which mean that We extract ninety per cent. and upward of valuable metal or metals by volatilization as chlorids and oxychlorids.

It will be obvious to those skilled in the art to which the invention relates that modifications, such as too much sulfur, requiring a wasteful amount of salt, may be made in detail without departing from the spirit thereof.

Having thus described the nature and objects of our invention, what we claim as new, and desire to secure by Letters Patent, is

I. The process which consists in effecting a mixture containing the ore, sulfur and a haloid of an alkaline or alkaline-earth metal,the relative proportions of the materials being substantially those quantitatively requisite to produce, when heated in the presence of oxygen, a haloid of the metal or metals to be extracted from the ore and a sulfate of the alkaline or alkaline-earth metal; roasting the mixture with free access of air and agitation at a temperature sufficient to effect the reaction mentioned; and volatilizing and recovering the metal values as haloids or oxyhaloids, substantially as described.

2. The process which consists in preparing a charge containing the ore, sulfur and a chlorid of an alkaline or alkaline-earth metal, the relative proportions of the materials being substantially those quantitatively requisite to produce, when heated in the presence of oxygen, a chlorid of the metal or metals to be extracted from the ore, and a sulfate of the alkaline or alkaline-earth metals; roasting the charge with free access of air and agitation at a temperature sufficient to effect the reaction mentioned; and volatilizing and recovering the metal values as chlorids or oxychlorids substantially as described.

3. The process which consists in preparing a charge containing the ore, sulfur and a chlorid of an alkaline or alkaline-earth metal, the relative proportions of the materials being substantially those quantitatively requisite to produce when heated in the presence of oxygen, a chlorid of the metal ormetals to be extracted from the ore and a sulfate of the alkaline or alkaline-earth metal; roasting the mixture with free access of air and agitation at a temperature sufficient to effect the IIO reaction mentioned; and volatilizing and recovering the metallic values as chlorids and oxychlorids from the fumes liberated, by subjecting them to the action of water, substantially as described.

4. The process which consists in preparing a charge containing the ore, sulfur and a chlorid of an alkaline or alkaline-earth metal, the relative proportions of the materials being substantially those quantitatively requisite to produce, when heated in the presence of oxygen, a chlorid of' the metal or metals to be extracted from the ore and a sulfate of the alkaline or alkaline-earth metal; roasting the mixture withfree access of air and agitation at a temperature sufficient to effect the reaction mentioned; and volatilizing and recovering the metallic values as chlorids or oxyehlorids from the fumes liberated by subjecting them to filtration and t0 the action of we.-

ter, substantially as described.

5. The process which consists in preparing a charge containing the ore, sulfur, and a chlorid of an alkaline or alkaline-earth metal, the relative proportions of the materials being substantially those quantitatively requisite to produce, when heated in the presence of oxygen, a chlorid of the metal or metals to be extracted from the ore and a sulfate of the l 5 alkaline or alkaline-earth metal; roasting the 

